Electrical protective device



B. H. SMITH.

ELECTRlCAL PROTECTWE DEVICE.

APPLICATION FILED OCT. 27, 19:5.

1,365,288. Patented Jan. 11, 1921.

INVENTOR WITNESSES UNITED STATES PATENT OFFICE.

BENJAMIN H. SMITH, OF TURTLE CREEK, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

Application filed October 2'7, 1915.

To all whom it may concern.

Be it known that I, BENJAMIN H. SMITH, a citizen of the United States, and a resident of Turtle Creek, inthe county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Electrical Protective Devices, of which the following is a specification.

My invention relates to electrical protective devices and particularly to relay switches and systems that are employed for tripping circuit interrupters, or operating other devices, upon the occurrence of predetermined circuit conditions.

One object of my invention is to provide a relay system of the above indicated character that is effective in operation and simple and economical in construction.

Another object of my invention is to provide a switch for a relay system of the character above indicated that shall operate satisfactorily, irrespective of the vibration of the relays.

Heretofore, considerable diiiiculty has been experienced with the contact members of relays and similar devices. This difiiculty has been due mainly to the arcing of the contact members, which at times, especially when the contact members vibrate because of excessive overloads, causes the relays to be ineffective and unreliable in operation.

According to the present invention, I provide a switch for a relay system having an actuating winding that is normally energized in accordance withthe current traversing the relays, and a controlling winding that is short-circuited by the contact members of the relays. A device of this type has the advantage that, when the contact members are engaged, if only for an instant, the switch is effectively actuated, irrespective of the subsequent vibration of the relay contact members. i

In the accompanying drawing, Figure 1 is a diagrammatic view of a part of a relay system embodying my invention; Fig. 2 1s a top plan view of a relay switch embodying my invention; and Fig. 3 and Fig. 4 are side and front elevational views, respectively, of the switch shown in Fig. 2.

A typical system in connection with which my present invention may be employed coinprises an alternating-current circuit 1 that is adapted to be interrupted by means of a Specification of Letters Patent.

PatentedJan. 11, 1921.

Serial No. 58,128.

circuit interrupter 2 and, in series with one conductor of which, is the primary winding 3 of a current transformer 41, the circuit of the secondary winding 5 of which includes the winding 6 of a relay switch 7, the windmg 8 of a reverse-energy. relay 9 and the winding 27 of an overload relay 11. The winding 10 of the relay 11 is connected in close circuit relation with the primary winding 12 of a saturable transformer 13 and the secondary winding 14 of the transformer is connected in close circuit relation with a winding 15 of the relay 11.

The relay 9 is provided with a potential winding 16 that is connected to the secondary winding 17 of a potential transformer 18, the primary winding 19 of which is connected across the conductors of the circuit 1. The windings 8 and 16 of the relay 9 surround portions of a stationary magnetizable core member 20 and are adapted to cooperate therewith to actuate an armature 21 that is mounted on a shaft 22. The shaft 22 is provided with a movable contact member 23 that is adapted to engage a stationary contact member 2 1 when the energy traversing the circuit 1 reverses. A spring 25 is adapted to bias the contact member 23 to its open position, and permanent damping magnets 26 are provided for retarding the movement of the armature 21. a

The relay 11 is provided with a winding 27 that is also connected in circuit with the secondary winding 5 of the transformer 4. The winding 27 is provided with a number of taps for facilitating the adjustment of the actuating current of the relay 11. The wind ings 10, 15 and 27 surround portions of a stationary magnetizable core member 28 and are adapted to cooperate therewith to actuate an armature 29 in accordance with the current that traverses the circuit 1. The armature 29 is mounted on a shaft 30 upon which is alsomounted a movable contact member 31 that is adapted to engage a stationary contact Inember32. The shaft 30 is provided with a spring 33 that is adapted to bias the contact member 31 to its open position, and the armature 29 is provided with damping magnets 34 for controlling the movement of the same. The saturable transformer 13 is provided for controlling the operation of the relay 11 and is so proportioned that the time element of operation of the relay shall be substantially inversely proportional to the current traversing the circuit 1 up to predetermined current values and substantially invariable or definite above these predetermined values, substantially as set forth in copending a aplication, Serial No. 771,888, filed by I). H. mith and A. W. Copley, June 5, 1913, and assigned to the Westinghouse Electric and Manufacturing Company.

The contact members 23, 24, 31 and 32 are connected in circuit with an auxiliary winding 35 f the switch 7. The switch 7 is provided with contact members 36 and 37 that constitute the separable terminals of a circuit 38 comprising a source of electromotive force 39 and the winding 40 of a tripping electromagnet 41.

The switch 7 comprises a stationary E- shaped magnetizable core member 42 and a pivotally mounted E-shaped magnetizable core member 43. The core members 42 and 43 are so disposed that the respective legs thereof are adjacent but separated by air gaps 44, 45 and 46. A spring or other resilient member 47 is disposed between the core members 42 and 43 for the purpose of normally maintaining the air gap 46 relatively Wider than the air gap 44. The contact members 36 and 37 are mounted on insulating members 48 and 49, respectively, that are attached to the respective E-shaped core members 42 and 43. The winding 6 loosely surrounds the inner legs 50 and 51 of the core members 42 and 43, respectively, and the winding 35 loosely surrounds the legs 52 and 53 that are separated by the relatively small air gap 44.

Under normal conditions of operation, the contact members 23 and 24 are disengaged and are adapted to be engaged when the energy traversing the circuit 1 reverses, and the contact members 31 and 32 are adapted to be engaged when the current traversing the circuit 1 has reached a predetermined value, either after a definite time interval or a time interval that is inversely proportional to the value of the current traversing the circuit 1. The current that traverses the winding 6 of the switch 7 produces a magnetic flux that divides between the paths afforded by the outer legs of the E-shaped core members 42 and 43. When the contact members 23, 24, 31 and 32 are engaged, the winding 35 is short-circuited and an electromotive force is induced therein by the mag netic flux produced by the winding 6 that tends to prevent the magnetic flux from traversing the legs 52 and 53, and, consequently, the contact members 36 and 37 are engaged because the magnetic flux must necessarily traverse the legs 54 and 55 that are normally separated by the air gap 46' lVhen the contact members 36 and 37 are engaged, suflioient current traverses the winding 40 to cause the tripping electromagnet 41 to trip the circuit interrupter 2.

Since the contact members 23, 24, 31 and are not required to interrupt excessive values of current, and since they are merely used as short-circuiting switches, it will be understood that the switch 7 will operate upon the first engagement thereof, and the switch 7 will not be subject to improper operation because of subsequent vibration of the relays 9 and 11.

vi hile I have shown and described my invention as applied to the tripping of a circuit interrupter, it may obviously be employed for other purposes, if desired, with out departing from the spirit and scope of the invention.

I claim as my invention:

1. In an electric circuit, the combination with a relay device having an actuating winding, of a relay switch comprising a magnetizable stationary member of Eshape, a movable magnetizable member of E-shape, an actuating winding surrounding the cen tral legs of said members and connected in circuit with the actuating winding of the relay device, and a restraining winding surrounding one pair of adjacent legs of the core members and adapted to be controlled by the relay device.

2. In an electric circuit, the combination with a relay, of a relay switch therefor comprising a stationary magnetizable member of E-shape, a pivotally mounted magnetizable member of E-shape, movable and stationary contact members mounted thereon, a winding surrounding the central legs thereof that is connected in circuit with the winding of the relay, and a second Winding for preventing the equal distribution of magnetic flux through the outer legs thereof, the circuit of the said second winding being controlled by the relay.

3. A switch comprising two relatively movable magnetizable members of substantially E-shape, coiiperating contact members mounted thereon, an actuating Winding surrounding the central legs of the magnetizable members and a relay-controlled second winding surrounding one pair of ad'acent legs of the magnetizable members or causing an unequal distribution of magnetic flux through the outer legs thereof.

4. A switch comprising two relatively movable magnetizable members of Eshape having their corresponding legs adjacent to each other, an energizing winding surrounding the central legs and a relay-controlled second winding surrounding one pair of the outer legs for precluding the equal distribution of magnetic flux through the outer legs under predetermined conditions.

5. A switch comprising two relatively movable magnetizable members of E-shape having their corresponding legs adjacent to each other, an energizing winding surrounding the central legs and a relay controlled second winding surrounding one pair of the outer legs for precluding the e ual distribution of magnetic flux through t e outer legs when it is close-circuited.

6. A switch for a. relay comprising two relatively movable magnetizable members of E-shape having their corresponding legs adj acent to each other, an energizing winding surrounding the central legs, a spring disposed between one pair of outer legs and a winding controlled by the relay surrounding the other pair of outer legs for precluding the equal distribution of magnetic flux through the outer legs under predetermined conditions.

7. A switch for a relay comprising two magnetizable members of E-shape, cooperating contact members mounted thereon, a spring for holding the contact members out of engagement, an actuating winding surrounding the central legs of the members and connected in series with the actuating winding of the relay and a winding surrounding one pair of adjacent legs of the members and controlled by the relay for permitting the engagement of the contact members under predetermined conditions- In testimony whereof, I have hereunto subscribed my name this 23rd day of Oct, 1915.

BENJAMIN H. SMITH. 

